This invention relates to a process for preparing 3-iodomethyl cephalosporins. In particular, it relates to a process for preparing 3-iodomethyl substituted cephalosporins from 3-acetoxymethyl and 3-carbamoyloxymethyl substituted cephalosporins and a trialkylsilyl iodide.
Trimethylsilyl iodide is known to dealkylate simple alkyl esters of carboxylic acids, M. A. Jung et al., J. Amer. Chem. Soc., 99, 968 (1977), Ho and Olah, Proc. Natl. Acad. Sci. U.S.A. 75 (1978). A mixture of iodine and phenyltrimethylsilane has been described as effective in the deesterification of like esters, Ho and Olah, Synthesis, 417 (1977). Ethers and acetals as well as alkyl esters are dealkylated with trimethylsilyl iodide prepared with chlorotrimethylsilane and sodium iodide, Morita et al., J. Chem. Soc. Chem. Comm. 1978, pp. 874-875. The same reagent has been employed to reduce dialkyl and diphenyl sulfoxides, Olah et al., Synthesis, 583 (1977) and Olah et al., Synthesis, 61 (1979).